1. Field of the Invention
This invention relates to the construction of a loading coil for the antennas of the type adapted for use in the citizen frequency band and mountable at the roof, trunk lip or rain gutter of automobiles.
2. Description of the Prior Art
There are known the antenna devices designed to receive the radio waves of the citizen band and mountable at the roof, trunk lip or rain gutter of automobiles, but it was hardly possible to adapt an antenna which resonates with the wavelength of the citizen band frequencies, with its own length on an automobile which moves on the road surface. Therefore, it has been generally practiced to insert a loading coil to a position close to the feeding point of the antenna to effect resonance with an antenna which resonates with a shorter wavelength than the citizen band. Also, in order to reduce the voltage standing wave ratio (V.S.W.R.) by preventing generation of the stationary waves in connecting the coaxial cable to said loading coil, it has been attempted to match the impedance of the antenna with that of the coaxial cable by leading out the tap from the middle part of the loading coil. For effecting such lead-out of the tap from the loading coil, it has been common practice to solder the lead-out wire to the coil wire and connect said lead-out wire to the coaxial connector by passing said wire through the inside of a bobbin on which the loading coil wire was wound. However, the work for leading out the tap from the loading coil and connecting it to the coaxial connector was laborious and time-consuming, and hence simplification of this tap lead-out step has been strongly requested.
Also, as the tap lead-out wire from the loading coil is connected to the coaxial connector assembly by soldering or such means, the bobbin having wound thereon the loading coil and the coaxial connector assembly have been initially formed severally from each other and they have been integrated after connecting the tap lead-out wire from the loading coil to the coaxial connector assembly. Therefore, additional labour and time has been required for forming the loading coil.